In a connecting structure between a rotary shaft and a metal plate and a method of connecting them together, in which the metal plate can be joined to the rotary shaft with a high degree of accuracy with high strength at a low manufacturing cost without causing eccentricity, inclination, or the like as far as possible, a large-diameter shaft portion and a small-diameter shaft portion are connected to each other with a predetermined difference in diameter so as to form therebetween a shoulder surface perpendicular to an axis of rotation, plural stripes of coining indents extending in a direction of shaft length are formed on the outer peripheral surface of the small-diameter shaft portion, a circular-shaped mount hole adapted to be fitted onto the small-diameter shaft portion is formed in the metal plate, the mount hole of the metal plate is press-fitted onto the small-diameter shaft portion so as to be subjected to plastic deformation by the coining indents, a portion surrounding the mount hole on one side surface of the metal plate is pushed against the shoulder surface, and the outer peripheral surface of the small-diameter shaft portion and the mount hole of the metal plate are joined together by laser welding or the like.